The present disclosure relates generally to methods of recovering alcohols from aqueous solutions. More specifically, in certain embodiments, the present disclosure relates to solvents useful for extracting alcohols from aqueous solutions and associated methods.
The extraction of hydrocarbons from deepwater oil and gas reservoirs requires the transportation of a production stream from the reservoirs to facilities for processing. Water, along with oil and gas, may be included in these production streams. During transportation, if the temperature of the production stream is low and the pressure is high, the system can enter the hydrate region where gas hydrates form. Gas hydrates are solids and behave like ice and, if formed in large quantities, may plug the pipeline. Hydrates may also plug or cause malfunction of other units, such as valves, chokes, separators, heat exchangers, etc.
Several methods exist for limiting the formation of these hydrates in production streams. One such method is to add a hydrate inhibitor into the production stream to prevent the formation of these hydrates. An example of such a hydrate inhibitor is monoethylene glycol. Another example of such a hydrate inhibitor is methanol. The hydrate inhibitors added to the production streams may later be recovered from the product stream and recycled.
Although there are several methods for recovering the monoethylene glycol, the most commonly used in the art is boiling off the water. However, when the water is boiled off, contaminants may be left behind in the monoethylene glycol stream. These contaminants may be removed in a purification process. The most commonly used method in the art of monoethylene glycol purification is a two step process where divalent ions are knocked out of the solution with a strong alkali and a solid-liquid separation unit (e.g. a filter press) and then the solution is distilled to recover the monoethylene glycol.
These recovery and purification methods may be problematic for several reasons: (1) they require the boiling off of large quantities of water, (2) they allow for the precipitation of solids in distillation units, (3) they require a second distillation step of the monoethylene glycol before the monoethylene glycol can be recycled, and (4) they expose the monoethylene glycol to high temperatures which may cause degradation. These methods also typically have high energy requirements, costs, and footprints and typically require large chemical consumption. It is desirable to develop a method of extracting a hydrate inhibitor from an aqueous solution that does not suffer these drawbacks.